Ithaca Chasma /ˈɪθəkə ˈkæzmə/ is a valley (graben) of Saturn's moon Tethys, named after the island of Ithaca, in Greece. It is up to 100 km (62 mi) wide, 3–5 km (1.9–3.1 mi) deep and 2,000 km (1,200 mi) long, running approximately three-quarters of the way around Tethys' circumference, making it one of the longer valleys in the Solar System. Ithaca Chasma is approximately concentric with Odysseus crater.